RICHLAND — Federal officials plan to evict Caspian terns from two man-made islands in the Columbia River Basin to protect endangered salmon and steelhead.
The Army Corps of Engineers and Bureau of Reclamation believe that if they can get the salmon-eating birds to stop nesting on the islands, they will find new nesting areas outside the Columbia River Basin.
The two islands in the plan are Goose Island is in Potholes Reservoir near Moses Lake and Crescent Island, created from dredged material, in the Columbia River about nine miles south of the confluence with the Snake River near Wallulla, The Tri-City Herald reported Saturday.
According to data collected from fish tags that litter the island after birds digest the fish, about 370 pairs of terns nesting on Goose Island feasted on 14.6 percent of inland Columbia Basin steelhead from 2007 to 2009.
In 2004, about 530 pairs of nesting terns on Crescent Island are estimated to have eaten 22 percent of the Snake River steelhead. The tern population there has since dropped to about 420 pairs.
The birds also eat juvenile chinook and sockeye salmon.
The Corps plans to start with a test planting of willows on Crescent Island to see if they will grow and reduce the open ground terns favor for nesting. They nest on islands to reduce their exposure to predators such as coyotes, weasels and rodents.
Temporary ropes hung with flags also could be set up to discourage nesting, particularly if birds try to relocate from Goose Island.
If more action is needed the second year, workers would chase the birds off daily from late February to early July and would flatten dirt scraped up on the ground for a nest.
Hazing will not be done in the first year of the program because gulls already might be nesting.
Should bad weather, such as lightning, prevent workers from hazing the terns and some eggs are laid, the eggs could be taken. However, the management plan expects that only a few eggs a year would need to be removed.
Information from: Tri-City Herald, http://www.tri-cityherald.com